While devices have been developed for automatic control over syringe actuation, the size and power requirements of such devices suggest against their use in environments in which space is limited or external power is not readily available. Such devices have been employed for balloon inflation in various surgical procedures including the opening of strictures, or narrowings of bodily passages, such as in endoscopic dilation where a balloon is used to open an esophageal stricture. Another application is in balloon angioplasty. For example, such applications involve the use of a syringe for delivering pressurized fluid for inflating a balloon. However, in surgical settings, there tends to be minimal free space immediately proximate the surgical site, thus rendering large and complex syringe actuation devices inappropriate. Furthermore, the cost and complexity of such automatic devices make them appropriate for sequential, repeated use. Repeated use requires that the devices be cleaned, serviced, and periodically recalibrated, resulting in higher operating costs.
Without such devices, precise control over fluid dispensed from a syringe has typically required the manual manipulation of a syringe plunger by an operator. For example, a physician may apply axial pressure on a syringe plunger to force pressurized fluid into an attached balloon for inflation. Other mechanical interfaces have been proposed for coupling operator movements to the syringe piston. One example of such interfaces includes the use of threads between the plunger and the syringe barrel whereby rotation of the plunger results in a gradual axial progression (or regression) of the plunger. Reliance on human operation exposes the inflation or deflation procedure to significant variability in terms of total volume of pressure fluid dispensed, rate at which the fluid is dispensed, and susceptibility to drawback.
Consequently, there is a need for a compact and inexpensive device which can accurately control the dispensing of fluid from a syringe, particularly for balloon angioplasty applications. The compact size of the device would make it suitable for use in space-limited environments, while the lower cost would enhance its suitability for one-time or disposable use.